I was doing SuperSets a few days ago and my ball exploded! I had JUST finished with some triceps work and had put the weights down to stretch when KA-BLOOEY!!! I am just glad that I didn't have the weights in my hands when it happened. So - I really do think that doing the exercises on the ball makes them more effective, but I'm not sure I want to risk it anymore. How significant is the difference between doing them on the ball as opposed to doing them on a bench? I'll still use a ball for the core work and stuff without weights, but I'm not sure I want to risk using weights on it.